JACKSON, Miss. — John McCain had the Straight Talk Express. Scott Brown had his pickup. Donald Trump has his helicopter – and plane. Some candidates are as well known for how they get around as the races they have run. But trucker Robert Gray and his light-blue big rig may be the most unconventional yet.

Gray, whose soft-spoken approach earned him the CB handle “Silent Knight,” shocked Mississippi’s political establishment by winning the Democratic primary for governor this summer, beating two candidates with better funding and political organizations.

Experts have offered varying theories as to what happened, from vote meddling to the country’s growing anti-establishment mood, to the possibility that voters simply ticked off the first name they saw on the ballot.

During an interview near the governor’s mansion, Gray acknowledged his limited, borderline nonexistent, campaign. “The only people who knew I was running were the people when I went in to qualify,” he said.

While nearly 150,000 Mississippians voted for him, Gray was not one of them. He has said he was busy working that day. At the time he had no website, no Facebook page, no Twitter account, or even a recent photo — but he had bought a suit just in case he won.

Vicki Slater, a longtime trial lawyer, was expected to win the Democratic nomination with relative ease. According to Slater, she and her staff of six did direct mail, made live and automated calls to voters, earned newspaper endorsements, visited 50 counties, and got the backing of local democratic groups. Even the state party chair, Rickey Cole, was at her announcement. In all, the campaign estimates they spent about $300,000.

“It’s impossible, unless Mr. Gray has come up with some genius strategy where you can do nothing, spend nothing, go nowhere, and take 79 counties in a three-way primary …”Vicki Slater

Robert Gray figures he spent about $50 on gas to go to a handful of events. He won 79 of 82 counties.

Now he is looking ahead to a general election matchup against incumbent Republican Gov. Phil Bryant, despite facing a steep deficit in spending and name recognition. His sister estimates they’ve taken in about $2,400 since his victory. Bryant’s campaign has $2.8 million in cash on hand.

Gray even failed to mention to his mother Judie and sister Angela, now his de facto campaign manager, that he had paid the fee to qualify.

His mother told MSNBC she was in the voting booth when she first saw her son’s name on the ballot, and thought “that’s Robert.”

Gray’s sister recalls receiving a phone call from their mother about the startling revelation. “And she’s like ‘no, it’s him.’ And then she says ‘no, it’s just someone with his name, but I voted for him because he has the same name.’ And I was like ‘oh, okay’ and I went back to work,” his sister said.

Gray offers little in the way of policy specifics, but says his run was inspired by his faith and his passion to serve.

“They want a governor that wants to help, wants to do good, that wants to make the best of what’s available,” he said.

Bryant’s office declined to make him available for an interview, but said in a statement, “We congratulate Robert Gray on his victory in the Democratic Primary earlier this month. We will continue to run a positive, record-based campaign on Mississippi’s future, and we hope he will do the same.”

Gray is unlikely to get any substantial outside help. A spokesman for the Democratic Governors Association said the group is “monitoring Mississippi and all other governors’ races. We will make ongoing decisions on investment based on the competitiveness of the race.”

How the Robert Gray phenomenon happened

Some have suggested that Gray earned the nomination because his name appeared first on the ballot. Others have argued he may have benefited from having a traditional man’s name.

Others, like Vicki Slater, believe that the last remnants of Democrats’ southern hegemony may have helped lift Gray. Like many secessionist states, Mississippi was unbreakably in the hands of Democrats for generations until the past 20 years. But often candidates in local races here still run as Democrats, even if they’re more likely to support Republicans in statewide and federal contests.

“They had no interest in voting in the Democratic primary for state officials because they’re going to vote Republican in the fall,” former Mississippi Gov. Haley Barbour said. “So, they just voted for the first name on the ballot, at the top of the tickets, to get on down to where they could vote for sheriff, for supervisor, and for all the people that run the local government.”

Some have openly wondered whether Republicans meddled in the primary, noting the outcome of a deeply divisive U.S. Senate race just a year earlier.

The 2014 Republican primary was mired in scandal. In the heat of the race, supporters of Mississippi state Sen. Chris McDaniel faced criminal charges for allegedly photographing incumbent Thad Cochran’s wife in an assisted care home, then posting the images online. It was part of an effort to prove Cochran was carrying on a long-term inappropriate relationship with a staffer, who he later married after his wife’s death.

With the national press corps watching, McDaniel tapped into tea party support to shock the state’s establishment network, forcing Cochran into a runoff. After finishing second, PACs backing Cochran responded by turning out African-American support in droves. They helped deliver Cochran a stunning victory just three weeks later.

Slater has called the weeks after the loss in the 2015 primary “a grieving process.”

“I don’t have any facts to make me think that it was something insidious, other than the fact that in the last three primaries that we’ve had, the Republicans have stooped so low as to be taking pictures in nursing homes, and breaking into courthouses, and all of that kind of thing,” she told MSNBC. “They do that to each other, so I wouldn’t be surprised if they did it in a Democratic primary, but I don’t have any facts to make me think that.”

Joe Nosef, chairman of the Mississippi Republican Party, refuted the implication. “I categorically deny any Jedi mind trick-related activity with regard to Robert Gray,” he said.

“I could believe someone said go put your name on the ballot we’ll pay your fee,” Hall said, but added Slater failed to establish name ID despite running a well-funded campaign. “The full weight of the Democratic party gets you second place to a no-name candidate.”

“I think that when I found out what happened, then I’ll be at peace with it, whatever it was,” Slater said. “But, it’s impossible, unless Mr. Gray has come up with some genius strategy where you can do nothing, spend nothing, go nowhere, and take 79 counties in a three-way primary — unless he’s got some sort of genius strategy for that, something else was going on.”